[XeTeX] Problem with xelatex/fontspec/xparse.sty with miktex2.9

[Joseph Wright]

On 01/07/2011 03:50, sjo wrote:
> Hi, I have just installed miktex2.9. The use of \usepackage{fontspec}
> produces and Undefined control sequence error in xparse.sty:
> 
> ------------
> % !TEX TS-program = xelatex
> % !TEX encoding = UTF-8
> \documentclass[11pt]{article}
> \usepackage{fontspec}
> \begin{document}
> Problem with xparse.sty
> \end{document}
> --------------
> Error:
> ("C:\Program Files (x86)\MiKTeX 2.9\tex\latex\l3packages\xparse\xparse.sty"
> ! Undefined control sequence.
> <argument> \filename
> l.57 ...\filedate}{\fileversion}{\filedescription}
> ?
> -----------------------------------
> 
> I had to install l3packages and other l3* stuff to get xelatex to work
> with the above file.
> 
> Any help would be much appreciated.
> 
> Jon

This is a transitory bug in the LaTeX3 packages. A fix was uploaded to
CTAN last night, but will take a few days to make it into MiKTeX. In the
meantime, you can edit

C:\Program Files (x86)\MiKTeX 2.9\tex\latex\l3packages\xparse\xparse.sty

replacing the line

  {\filedate}{\filedate}{\fileversion}{\filedescription}

by

  {\ExplFileName}{\ExplFileDate}{\ExplFileVersion}{\ExplFileDescription}

Apologies for this!

(Normally, editing a MiKTeX-installed file would not be recommended, but
in this case the next time you do an update MiKTeX will only be doing
the same thing anyway, so there should not be an issue.)
-- 
Joseph Wright